Fatigue Strength of Typical Structural Elements Made of Polymer Composite Material

It is necessary to ensure their fatigue strength, when designing structures made of composite materials operating under vibration conditions. This requires experimental data on the characteristics of fracture resistance due to high-cycle fatigue. The standard approach to determining these characteristics involves long-term, expensive experimental work. In the case of composite materials, the fatigue resistance characteristics of material samples and elements of full-scale structures may differ significantly. Therefore, it is necessary to conduct fatigue tests of expensive full-scale structures or typical elements. A search for accelerated fatigue testing methods is needed. The method of infrared thermography is successfully used to quickly assess the fatigue limit of materials. It is based on the effect of self-heating of the material under cyclic loads exceeding the fatigue limit. In this work, this method was applied to two elements of a full–scale structure: a shell with shell with L-shaped flange and а shell with trapezoidal stiffeners made of laminated carbon fiber. The samples cut from the shell was subjected to block cyclic loading on a vibrating stand. Self-heating was recorded during loading using an infrared camera. The obtained estimates of the fatigue limit are consistent with the results of standard fatigue tests.